Capped AIV = crummy idle and smoke?

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I have a 1990 240 5spd hb (KA24E). This thing has the AIV - the black box next to the airbox with the hose going inbetween. I tried to cap it off temporarily by taking off the hose and duct taping both openings very well, but the car idled like **** and revving the motor produced an unsightly smoke out of the tailpipe.

What in the hell am I doing wrong?

[MrMigs]

If I remember correctly, the hose you're messing with is either part of the PCV(Positive Crankcase Vent.) System or the EGR(Exhaust Gas Recirculation) System. So then basically, without going into much more detail... if you cap something off, you're going to get problems. :eek:

[gschroeder78]

I removed the box and left the AIV valve and didn't cap anything off. Your apparently supposed to but a breather filter on it though but I haven't done that yet. A year and my idle is fine. Now on my Z32, you do have to cap off any of the open lines or you will get vacumn leakage. I know it's right on the Z32 but I really have no idea on the S13. Just wanted to say you can probably uncap the opening.

[sph33r]

I completely removed mine earlier this year. If I remember correctly, there are electronics on the valve assembly. Did you unplug those? Perhaps it's still trying to function but can't get any air so it's causing this. In my case, I removed the AIV valve and tubing and welded the hole shut on my header I was installing. The car has been running fine for months.

[/etc/shadow]

Yeah, I left it uncapped (except capped the airbox side) and it seems to be running well now. Thanks!

[brage]

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